Howdy Jackie. It’s not a secret technique that will improve your vocabulary overnight, but reading is the most efficacious method to make that jump from “competent user” to “skilled user”. Memorizing lists of vocab, like from GRE or SAT prep books, or having stacks of flashcards; can be useful for preparing for those tests, but the inorganic way the words are presented means most of the definitions are not going to be remembered after test day. To clarify, I don’t just mean reading newspaper articles or blogs, although that can have its place, I mean literature. If you can make reading target-language books (that are *slightly* above your level) a daily habit, your mastery of the lexicon will grow slowly but noticeably. You might want to consider taking classes, maybe once every week or two, to double check your comprehension of difficult passages with a native speaker. Good luck!